The researchers studied how adding copper to organic soil affects the distribution of copper, manganese, zinc, and iron. They found that adding copper increased the availability of manganese and zinc in the soil, making them more accessible to plants. The added copper did not decrease the availability of iron. In soils with added copper, most of the copper was tightly held and not easily extractable. Overall, the study suggests that adding copper to soil can enhance the uptake of certain essential nutrients by plants without causing physiological stress.